Staircase units have both active and hazard impacts on whole structure under earthquake. The existence of these impacts should not be neglected during designing process. Three sets of nonlinear finite element (FE) models of different types are finely built with and without staircase units, upon which dynamic earthquake analysis and pushover analysis are carried out to simulate the real earthquake disaster. Comparisons of overall properties, pushover performances, seismic response and internal force of elements are summarized and discussed between two models of a set. Potential dangerous elements are found while the reasons are generalized. Suggestions upon designing process are given as well.